U.S. Pat. No. 4,147,855 describes compositions which can be stored with exclusion of water and cross-link on the addition of water at room temperature to give elastomers and which comprise diorganopolysiloxane containing end groups capable of condensation, aminosilane or ketoximosilane and phosphoric acid esters. The use of acid phosphoric acid esters, that is those having hydroxyl groups, in amounts which exceed the amount neutralized by the basic nitrogen compounds liberated during the cross-linking are excluded. U.S. Pat. No. 4,147,855 also states that the acid phosphoric acid esters have the disadvantage of causing degradation of the polymers. The reference also shows elastomers that have a low tensile strength at elongation. Such elastomers are desirable for joint seals applications.
EP 246 651 discloses cross-linkable compositions which comprise organopolysiloxane containing end groups capable of condensation, tri- or tetraalkoxysilane or oligomers thereof and silyl esters of phosphoric acid. Elastomers which adhere firmly to substrates to which they have been applied are obtained, however, the strength of these elastomers is not sufficient for coatings exposed to mechanical stresses.
Therefore it is the object of the present invention to provide compositions which are based on diorganopolysiloxane and are cross-linkable giving elastomers and which contain no toxic curing catalysts, such as tin catalysts. These elastomers have a high tensile strength at elongation and are suitable for the production of coatings.